A GCOS Reference Upper-Air Network (GRUAN) workshop to develop network design and expansion criteria was held in Fürstenwalde, Germany, from 13 to 15 June 2012. GRUAN’s goal is to provide reference-quality measurements of upper-air Essential Climate Variables (ECVs) to meetthe needs of the climate research and monitoring communities and to fill a void in the globalobserving system. Upper-air observations at sites within the GRUAN network provide long-term, high-quality, error-characterized climate records designed to serve GRUAN’s primary user communities.

The vision for a fully implemented GRUAN is an expanded network eventually comprising 35-40 sites. This expansion must be carefully planned to most effectively advance GRUAN’s scientific objectives. The purpose of this workshop was to understand the network design requirements to meet the needs of four primary users of GRUAN data, i.e.:

• climate change detection and attribution,
• satellite calibration and validation,
• atmospheric processes research, and
• numerical weather prediction.

This report summarizes the key outcomes of that workshop.

v1.0 (2014-11-03)

Bodeker et al., Outcomes of the GRUAN NetworkExpansion Workshop, GRUAN-RP-4, v1.0 (2014-11-03).